Stripline board connector



Nov. 16, 1965 c, 5, M Y 3,218,585

STRIPLINE BOARD CONNECTOR Filed March 10, 1964 2 Sheets-Sheet 1 FIG. I

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,3 54 VII 3 INVENTOR. CHARLES B. MAY

ATTORNkY.

Nov. 16, 1965 c, 5, Y 3,218,585

STRIPLINE BOARD CONNECTOR Filed March 10, 1964 2 Sheets-Sheet 2 FIG. 7.

68 r I 80 66 k 80a my INVENTOR.

CHARLES B. MAY

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ATTORNEY.

United States Patent 3,218,585 Patented Nov. 16, 1955 flice 3,218,585 STRIPMNE BQARD CGNNECTOR Charles B. May, Ridgecrest, (Iaiif, assignor to the United States of America as represented by the Secretary of the Navy Filed Mar. 10, 1964, Ser. No. 3545318 (Ilaims. (Cl. 333-34) (Granted under Title 35, U.S. (lode (1952), see. 266} The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to connectors and has particular reference to RF (radio frequency) connectors suitable for mechanically and electrically joining stripline boards. More specifically it concerns RF connectors of such character as to yield minimal VSWR (voltage standing wave ratio) in effecting electrical connection between stripline boards designed for operation at microwave frequencies.

Stripline boards have evolved from waveguides and waveguide devices of coaxial type, possess certain features and characteristics of both rectangular pipe and coaxial type waveguides, and are generally designed for and are finding increasing application at microwave frequencies in the 1 to gc./s. (gigacycles per second; kilomegacycles per second) range where they present considerably smaller size and weight than conventional waveguide and coaxial transmission lines and devices, together with many other advantages. Stripline board of symmetrical, double-ground-plane type, sometimes termed triplate, consists of a narrow, thin, metallic strip, termed the center conductor, sandwiched between two comparatively wide sheets of low-loss dielectric material, the outer sides of the dielectric sheets being covered with conductive plating, foil or sheets termed ground-planes.

Because of their considerably smaller size and weight, and other advantages, stripline boards are often employed in assemblies in the RF sections of guided missiles of homing type wherein, in addition to design for use as transmission line, the stripline board center conductor may be formed in hybrid junction and other configurations suitable to effect signal processing as desired. In these and other uses it is of course necessary to provide electrical connection between stripline boards, and it has been the practice heretofore to accomplish this by means of coaxial connectors having the two ends thereof modified in some suitable manner to be able to effect electrical connection, via the coaxial connector, from the center conductor and both ground planes of one stripline board to the center conductor and both ground planes of the other stripline board. Such coaxial connectors and modification techniques as applied for use with stripline boards, however, have never been fully satisfactory from either mechanical or electronic standpoints. From an electronic standpoint, for example, coaxial type connectors and stripline boards transmit RF energy in different modes, and it is perhaps for such reason that satisfactorily smooth transition between stripline board and coaxial connector cannot be achieved; in any event it is found that RF energy reflections arise at or near the stripline board and connector junctions, to an extent resulting in comparatively large VSWR. It is of course desirable to keep the reflection small, and of substantially constant magnitude relative to frequency when operation must take place over a band of frequencies.

Accordingly, it is an object of the present invention to provide a new and improved RF connector for mechanically and electrically joining stripline boards.

It is another object of the invention to provide an RF connector which can couple stripline boards easily, securely and reliably.

It is another object to provide a compact connector for effecting electrically smooth coupling between stripline boards.

It is another object to provide a stripline board con nector presenting substantially Zero insertion and radiation loss characteristics.

It is a further object to provide a stripline board and connector assembly presenting negligible transmission discontinuities at the connector junctions and correspondingly very small reflection and minimal VSWR characteristics.

These and other objects and advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following description when considered in connection with the accompanying drawing wherein:

FIG. 1 is a face view of one embodiment of the new and improved RF connector;

FIG. 2 is an internal side view of one section of the connector shell and a cross-sectional view of dielectric insert structure, taken on the line 2-2 of FIG. 1;

FIG. 3 is a top view of the FIG. 1 connector;

FIG. 4 is a side view, partly in section, of one of a pair of caps employed for clamping stripline boards to the connector body;

FIG. 5 illustrates, principally in cross-section, an assembly of the FIG. 1 connector and a pair of stripline boards, taken along the line 55 of FIG. 6;

FIG. 6 is a view of the connector and stripline board assembly, partly broken away to illustrate the comparative width of center conductor, taken along the line 6-6 of FIG. 1;

FIG. 7 is a face view of another embodiment of the new and improved RF connector;

FIG. 8 illustrates, principally in cross-section, an assembly of the FIG. 7 connector and a pair of stripline boards; and

FIG. 9 is a view of the FIG. 8 connector and stripline board assembly taken in the direction of arrow 9 in FIG. 8.

The invention is here presented in the form of two distinct embodiments, FIGS. 1 to 6 concerning one in which the connector is designed for use with stripline boards to be associated in such manner that their central conductors extend away from the connector in the same direction, and FIGS. 7 to 9 concerning another embodiment in which the connector is designed for use with stripline boards to be associated in such manner that their central conductors extend away from the connector in opposite directions. The connector in accordance with the present invention, further, may be secured to the stripline boards either by use of end caps and bolting technique as illustrated for the first embodiment, but preferably by use of grooves and retaining rings entered therein as illustrated for the second embodiment. Characteristics or features common to both embodiments of the new and improved connector are the provision of a body member having an electrically conductive shell including two outer cylindrical portions extending from a flange portion, a channel of rectangular cross section extending through the shell and terminating in a pair of windows in the cylindrical surfaces of the outer portions, the channel being filled with dielectric material and a strip conductor being centered therein and terminating in tabs extending beyond the Windows, and the shell being formed as two separable complementary parts to facilitate manufacture and assembly.

Referring in greater detail to the connector embodiment illustrated in FIGS. 1 to 4 and to the stripline board and connector assembly illustrated in FIGS. 5 and 6, the connector comprises a body member 20 including an electrically conductive shell 22 which, except for the larger size flange portion 24, is of cylindrical configuration, having outer portions 25 and 28 extending along a reference axis 30. Shell 22 is provided with a channel 32 which extends in arcuate manner between windows 26 and 28 opening to the cylindrical surfaces of outer portions 26 and 28, respectively, the channel being of rectangular cross-section as best shown in FIG. 6. Shell 22 is formed as two complementary sections 22a and 22b separable along a parting plane extending through axis 30 and centrally through channel 32 and windows 26' and 28', for ease of manufacture and assembly of the several component parts of body member 20. When fully assembled, body member 20 includes a suitable dielectric material (of such type as normally employed in stripline boards) here provided as conformably-shaped inserts 34, 36 which fill channel 32, and which has a thin strip conductor 38 centered therein, terminating in two tabs 38a and 3811 extending beyond the windows 26' and 28. In this embodiment, further, flange portion 24 of the body member shell 22 is provided with threaded holes 40, for use of the body member in connection with end caps 42 (FIG. 4) having perforations 44 to pass bolts 46, with which to clamp the stripline boards 48 and 50 between caps 42 and flange portion 24 of the body member 26 as indicated in FIG. 5.

In assembling the connector with say the upper stripline board 48, by way of example, the stripline boards upper dielectric plate 48a together with its ground plane conductor 48b are first removed, outer portion 26 of connector body member 20 (with its center conductor tab 38a bent upwardly) is inserted through the cylindrical bore 52 of the stripline boards lower ground plane conductor 48c and dielectric plate 48d, tab 38a is then bent downwardly against center strip conductor 54 of the stripline board, outer portion 26 of connector body member 20 is then further inserted through the cylindrical bore 52 of the upper dielectric plate 48a and its ground plane conductor 48b, and the stripline board and connector body member are clamped together, with tab 38a and center strip conductor 54 in electrical contact, by means of end cap 42 and bolts 46 as indicated.

Referring now to a second connector embodiment and its assembly with stripline boards as illustrated in FIGS. 7, 8 and 9, this connector comprises a body member 60 which is basically the same as that already described, except for the particular configuration of its channel 62 which extends in doubly arcuate manner (FIG. 8) between oppositely facing windows 64 and 66, the corresponding S-configuration of its conformably-shaped dielectric inserts 68 and 70, the corresponding S-configura tion of thin strip conductor 72 which terminates in oppositely-directed tabs 72a and 72b, and the grooves 74 which are provided in body member 60 for use with retaining rings. Assembly of the connector 66 with the stripline boards 7 8 and 89 is made in essentially the same way as described for the preceding embodiment. Tabs 72a and 72b of the connector center conductor 72 overlie the center conductors 78a and 80a of stripline boards 78 and 80, respectively, with the stripline boards and their center conductors extending in opposite directions relative to connector 60. The body member components are held together and in association with the strip line boards 78 and 80 by the retaining rings 76 which resiliently clamp into the grooves 72 of body member 60.

It has been found in actual practice that RF connectors in accordance with the present invention and designed for use at a nominal frequency of about 3.0 gc./s. present a comparatively low and substantially constant VSWR over a test frequency range of about 2.0 to 4.0 gc./s. It will also be understood that RF connectors as described can be designed for transition between stripline boards having any characteristic impedance values, and further that impedance transformation can be made within the RF connector itself where this may be required for electronically joining two stripline boards having different impedance characteristics.

Obviously many modifications, variations and applications of the invention are possible in the light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

What is claimed is:

1.1A connector for mechanically and electrically joining two stripline boards in substantially parallel relationship, wherein said stripline boards each include a comparatively narrow strip conductor sandwiched between a pair of dielectric sheets having ground plane conductors on their outer surfaces and wherein, for acceptance of said connector, said stripline boards are each provided with a cylindrical bore extending transversely therethrough and positioned in lateral alignment with said narrow strip conductor which extends to said bore, said connector comprising:

(a) a body member having a reference axis therethrough,

(b) said member including an electrically conductive shell having two outer cylindrical portions extending along said axis, and a curved channel of rectangular cross-section extending through said shell from a window in the cylindrical surface of one of said outer portions to another window in the cylindrical surface of the other of said outer portions, said channel having one pair of its walls lying in planes parallel to said reference axis,

(c) dielectric material filling said channel,

(d) a comparatively narrow strip conductor centered in said dielectric material and extending along said channel, terminating in tabs extending beyond said cylindrical surfaces of said outer portions, and

(e) said shell being formed in two complementary parts separable along a parting plane extending through said axis and centrally through said channel and windows.

2. A connector for mechanically and electrically joining two stripline boards in substantially parallel relationship, wherein said stripline boards each include a comparatively narrow strip conductor sandwiched between a pair of dielectric sheets having ground plane conductors on their outer surfaces and wherein, for acceptance of said connector, said stripline boards are each provided with a cylindrical bore extending transversely therethrough and positioned in lateral alignment with said narrow strip conductor which extends to said bore, said connector comprising:

(a) a body member having a reference axis therethrough,

(b) said member including an electrically conductive shell having two outer cylindrical portions extending along said axis, and a curved channel or" rectangular cross-section extending through said shell from a window in the cylindrical surface of one of said outer portions to another window in the cylindrical surface of the other of said outer portions, said channel having one pair of its walls lying in planes parallel to said reference axis,

(c) dielectric material filling said channel,

(d) a comparatively narrow strip conductor centered in said dielectric material and extending along said channel, terminating in tabs extending beyond said cylindrical surfaces of said outer portions,

(e) said shell being formed in two complementary parts separable along a parting plane extending through said axis and centrally through said channel and windows; and

(f) retaining means adapted to be associated with said body member to maintain it in assembled and operative relationship with said stripline boards.

3. A connector for mechanically and electrically joining two stripline boards in substantially parallel relationship, wherein said stripline boards each include a comparatively narrow strip conductor sandwiched between a dielectric sheets having ground plane conductors on their outer surfaces and wherein, for acceptance of said connector, said stripline boards are each provided with a cylindrical bore extending transversely therethrough and positioned in lateral alignment with said narrow strip conductor which extends to said bore, said connector comprising:

(a) a body member having a reference axis therethrough,

(b) said member including an electrically conductive shell having two outer cylindrical portions extending along said axis, a flange portion positioned between and integral with said outer portions, and a curved channel of rectangular cross-section extending through said shell from a window in the cylindrical surface of one of said outer portions to another Window in the cylindrical surface of the other of said outer portions, said channel having one pair of its walls lying in planes parallel to said reference axis,

(c) dielectric material filling said channel,

(d) a comparatively narrow strip conductor centered in said dielectric material and extending along said channel, terminating in tabs extending beyond said cylindrical surfaces of said outer portions; and

(e) said shell being formed in two complementary parts separable along a parting plane extending through said axis and centrally through said channel and windows.

4. A connector for mechanically and electrically joining two stripline boards in substantially parallel relationship, wherein said stripline boards each include a comparatively narrow strip conductor sandwiched between a pair of dielectric sheets having ground plane conductors on their outer surfaces and wherein, for acceptance of said connector, said stripline boards are each provided with a cylindrical bore extending transversely therethrough and positioned in lateral alignment with said narrow strip conductor which extends to said bore, said connector comprising:

(a) a body member having a reference axis therethrough,

(b) said member including an electrically conductive shell having two outer cylindrical portions extending along said axis, a flange portion positioned between and integral with said outer portions, and a curved channel of rectangular cross-section extending through said shell from a window in the cylindrical surface of one of said outer portions to another window in the cylindrical surface of the other of said outer portions, said channel having one pair of its walls lying in planes parallel to said reference axis,

(c) dielectric material filling said channel,

(d) a comparatively narrow strip conductor centered in said dielectric material and extending along said channel, terminating in tabs extending beyond said cylindrical surfaces of said outer portions,

(e) said shell being formed in two complementary parts separable along a parting plane extending through said axis and centrally through said channel and windows; and

(f) retaining means adapted to be associated with said body member to maintain it in assembled and operative relationship with said stripline boards.

5. In combination:

(a) a pair of stripline boards, each including a center conductor sandwiched between a pair of dielectric sheets having ground-plane conductors on their outer surfaces, and each stripline board having, for acceptance of a connector, a cylindrical bore extending therethrough and positioned in lateral alignment with said center conductor which extends to said bore;

(b) a connector joining said stripline boards in substantially parallel relationship and with their bores in registry,

(c) said connector comprising a body member having a reference axis therethrough,

(d) said member including an electrically conductive shell having two outer cylindrical portions extending into said bores,

(f) windows in said cylindrical portions facing said stripline board center conductors,

(g) a channel extending through said conductive shell between said windows,

(h) dielectric material filling said channel,

(i) a conductor centered in said dielectric material and extending beyond said windows and in electrical engagement with said stripline board center conductors, and

(j) means maintaining said connector and stripline boards joined in mechanical and electrical association.

No references cited.

HERMAN KARL SAALBACH, Primary Examiner. 

5. IN COMBINATION: (A) A PAIR OF STRIPLINE BOARDS, EACH INCLUDING A CENTER CONDUCTOR SANDWICHED BETWEEN A PAIR OF DIELECTRIC SHEETS HAVING GROUND-PLANE CONDUCTORS ON THEIR OUTER SURFACES, AND EACH STRIPLINE BOARD HAVING, FOR ACCEPTANCE OF A CONNECTOR, A CYLINDRICAL BORE EXTENDING THERETHROUGH AND POSITIONED IN LATERAL ALIGNED WITH SAID CENTER CONDUCTOR WHICH EXTENDS TO SAID BORE; (B) A CONNECTOR JOINING SAID STRIPLINE BOARDS IN SUBSTANTIALLY PARALLEL RELATIONSHIP AND WITH THEIR BORES IN REGISTRY, (C) SAID CONNECTOR COMPRISING A BODY MEMBER HAVING A REFERENCE AXIS THERETHROUGH, (D) SAID MEMBER INCLUDING AN ELECTRICALLY CONDUCTIVE SHELL HAVING TWO OUTER CYLINDRICAL PORTIONS EXTENDING INTO SAID BORES, (F) WINDOWS IN SAID CYLINDRICAL PORTIONS FACING SAID STRIPLINE BOARD CENTER CONDUCTORS, (G) A CHANNEL EXTENDING THROUGH SAID CONDUCTIVE SHELL BETWEEN SAID WINDOWS, (H) DIELECTRIC MATERIAL FILLING SAID CHANNEL, (I) A CONDUCTOR CENTERED IN SAID DIELECTRIC MATERIAL AND EXTENDING BEYOND SAID WINDOWS AND IN ELECTRICAL ENGAGEMENT WITH SAID STRIPLINE BOARD CENTER CONDUCTORS, AND (J) MEANS MAINTAINING SAID CONNECTOR AND STRIPLINE BOARDS JOINED IN MECHANICAL AND ELECTRICAL ASSOCIATION. 